This invention relates to molding apparatus of the type in which molding material is injected into one or more mold sets to form one or more molded articles. More particularly, the invention relates to apparatus in which each of the mold sets comprises upper and lower molds adapted to be opened and closed relative to one another and adapted to be attached releasably to holding plates. When the apparatus is changed over to mold articles of a different type, the molds are detached from the holding plates and are replaced with different molds.